Proceedings of the Fourth International Coral Reef Symposium, 1981The Fourth International Coral Reef Symposium was conducted by the Marine Sciences Center, University of the Philippines, from 18-22 May 1981. The theme chosen for the Manila symposium was "The Reef and Man" as coral reefs are an important marine resource exploited by the local populations for their sustenance and livelihood. Emphasis was given to coral reef management, fisheries, and environmental stress, in addition to the more traditional areas.

A total of 275 papers were presented, some 50 of which were on resource management and environmental impacts. The symposium was attended by approximately 350 participants and 250 observers, with sizeable group of Russian and People's Republic of China scientists present for the first time.

Lepidisis olapa Muzik is a species of gorgonian (Coelenterata: Octocorallia) growing in deep water off Oahu,
Hawaii. Living colonies observed during submarine dives were luminescent when mechanically stimulated. Although
common in the order Pennatulacea, luminescence is apparently unusual in the order Gorgonacea, and has
never before been observed in colonies in their natural environment.

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2.

ICRS4Talbot, F.H. and A.J. Gilbert,
1982

A comparison of quantitative samples of coral reef fishes latitudinally and longitudinally in the Indo-West Pacific,

A comparison is made between quantitative samples of fishes from coral reef areas of leeward outer slopes
from 5°,14°,23° an,d 31 ° South Latitude along the East Australian coast. The first three show no significant differences
for number of individuals per sample or number of species per sample. Samples from the coral slopes at
Lord Howe Island (31 OS) showed no differences in numbers of individuals, but were significantly lower in species
numbers from each of the other three sites. Diversity (H") is also compared. A comparison of samples from all
habitats of one of these sites (One Tree Island Reef, 23°S) is made with samples from East Africa (Tutia Reef,
S OS) the latter having a much smaller species pool. No significant difference is found for number of individuals or
number of species per sample, or for diversity.

In the Takapoto lagoon (north Tuamotu), the individual measurements in situ of 150 T. maxima reveal a very
sl~~ gro~h rate, as the equation of von Bertalanffy shows: Lt = 124.33 (1 -@.26T). In the whole lagoon, 14
million gIant clams represent 530 tons of living matter, corresponding to a theoretical production of 12 kg per
hectare per year.
In the Takapoto lagoon the bivalve Arca ventricosa was studied (38.5 million individuals -340 tons of living
matter). In situ measurements taken in 1977 revealed another very slow growth: Lt = 103 (1 -0.94T).
In the ~naa lagoon (west ~~motu) the population of Cardium (ragum is.estimated at 600 million individuals
correspondmg to 2200 tons of liVIng matter. Growth fits the foIlowmg equatlon: Lt = 40 (1 -~.48). This enables
us to estimate the maxiInum theoretical production of 1.4 ton of meat per hectare per year.
On the outer reefs of Hao (Central Tuamotu), it takes 5 years for Tectarium grandinatus to reach 3 cm in size,
which gives it a growth rate somewhere between Tridacna's and Cardium's: Lt = 34.09 (1 -eo.25 T).

Regression models have been used in few quantitative coral reef studies. The present paper employs multiple linear regression using a stepwise techniqtre to generate a sub-model of the coral reef ecosystem. In the model the total biomass of corals on a particular reef is predicted at a statistically significant level from the component
biomasses of a subset of the coral species. The technique also ranks the species in terms of their contribution to
this prediction. Regression equations were established for Zhongjian Island and Zhaoshu Island of the Xishi
Islands.

The leeward fringing reef of Apo Island was subjectively divided into seven biotopes from the shoreward
margin to 35 m depth, Using scuba, one 300 m transect was placed along the depth contour corresponding to the
central axis of each biotope. and then point-sampled every 0.5 m. One hundred and ninety-seven species in 41
genera of hermatypic corals were sampled. The species-colony curve is used to define an adequate sample size. On
the basis of differences in species composition, growth form and diversity levels, the reef was divided into two major
communities, the reef flat and the outer reef slope, separated by a transition biotope, the reef crest. The reef
flat is characterized by a low species diversity and the dominance of ramose species, apparently well adapted to
strong abiotic and biotic stress. The outer reef slope is characterized by a high species diversity and the
predominance of plate and encrusting growth forms. Below 15 m, decreasing light, and substrate effects appear
to decrease species diversity.

Forty-nine reefs between 14°8 and 18°8 on the Great Barrier Reef were surveyed using the "manta tow"
technique. Large Acanthaster planci populations were recorded on four reefs and several showed evidence of recent
A. planci damage.

The abundance of the sea star Acanthaster on a Pocillopora reef in the eastern Pacific (Panama) has remained
relatively stable, ranging from about 7 to 30 individuals per hectare over the past decade (1970-1980). Periodic
removal of adult sea stars from the reef demonstrated a median immigration rate of 1.5 adults per month. A
shrimp, Hymenocerq, and a polychaetous annelid, Pherecardia, frequently attack and kill adult Acanthaster.
Hymenocera typically wounds the aboral surface or amputates an arm by picking and tearing with its chelae in
order to exposed and feed on the sea star's internal soft parts. Pherecardia are attracted to and enter the sea star
through openings produced by the shrimp and also feed on the internal soft parts. At any given time, 5-6% of the
sea star population is under attack by Hymenocera and about one-half of these sea stars are killed in 3-weeks
(after continuous feeding by the shrimp). About 0.6% of the sea stars are attacked simultaneously by shrimp and
worms, resulting in the death of all sea stars so assaulted in 1 week's time. The population size (N) of adult Acanthaster
is expressed as a function of adult immigration (I) and mortality (M) as follows,
dN/dt = I -MN
From observed immigration and mortality rates, the number of sea stars predicted on the reef in the limiting case
is 30, a value in fair agreement with the median abundance of 22 Acanthaster observed over a 3-year period
(1976-1978). Highly reticulated pocilloporid reefs offer shelter to shrimp and worm predators which appear to
limit a buildup in the numbers of A can thaster. Moreover, juvenile Acanthaster probably seldom recruit into this
kind of reef in large numbers because these predators are also effective in locating and killing small sea stars.

Acropora was present in Hawaii during the Miocene but disappeared from the geological record during the
Pleistocene. In the present (Holocene), Acropora appears to be in the process of recolonizing the archipelago.
Three species have been found. all with centers of distribution in the middle of the chain at French Frigate Shoals.
The history of the Hawaiian Archipelago shows that original colonization of Acropora in the Miocene or earlier
must have been by larval dispersal. Following Pleistocene extinction. recolonization appears to be underway by
way of larval disperal from Johnston Atoll via the subtropical counter-current. In Hawaii, no evidence of sexual
reproduction has been found. hence. large scale patterns of abundance may depend entirely on recruitment from
outside the archipelago.

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It is shown that coral adaptation to low light intensity is realized through interrelated reactions in the coralz,zoxanthe.llae complex. Zooxanthellae concentration in corals as well as the content of all photosynthetic
pI~ents m zoox:anthellae cells and the concentration of thylakoid membranes in their chloroplasts increases; the
n.atlve state of pIgments changes -mostly long-wave forms of chlorophyll-a and peridinin are accumulated. Efficlencyof
energy transport between molecules of peridinin and chlorophyll-a as well as efficiency of utilization of
absorbed light increases. Coral adaptation to shading in shallow waters and to low light intensity at great depths
is realized through the same adaptive mechanisms.

Many species of sponges in the coral reefs of Noumea harbour symbiotic algae. Some of them, which are prominent
species of the lagoon and may significantly contribute to its production, are studied at the ultrastructural
level.
Four types of algal-sponge associations are found:
1) Association with unicellular cyanobacteria. This association seems to be similar to those previously
described and is not studied here.
2) Association with a multicellular cyanobacterium. This is studied in a keratose sponge, PhyUospongia dendyi.
The cyanobacterium lives in the central part of this lamellar sponge; it is usually intercellular, but is mostly
in close contact with the sponge cells and is sometimes within large cellular vacuoles.
31 Dinoflagellate zooxanthellae, which in the Porifera were known to occur only in Mediterranean and Caribbean
clionids, are found in an encrusting clionid, which spreads on and bores in large areas of dead coral heads in
the lagoon. They are found also in two species hitherto classified in the family Spirastrellidae, but which actually
have a boring basal part and are to be considered as massive forms of clionids. The zooxanthellae are enclosed in
sponge cells (archeocytes). A surprising fact is that, while in scleractinian corals zooxanthellae have been shown
to enhance calcification, in sponges zooxanthellae are found only in calcium carbonate-destroying species. This
point is discussed in the light of current ideas on the mechanisms linking photosynthesis and calcification in her-
matypic corals.
41 The Haplosclerid Gellius cymiformis is intimately associated with an alga, the thallus of which is used as a
support by the sponge. This compound organism is in certain places the most common "alga" of the sandy substrata in the lagoon.

The biomass of polyps and zooxanthellae, the rates of photosynthesis and respiration, and the rates of
heterotrophic feeding (suspension feeding, consumption of DOM and predation) were evaluated in 27 common
coral species of the Great Barrier Reef. The total content of Corg in corals varied within 1-7%. The greater content
of Corg was found in the corals Montipora and Porites; the biomass of polyps in those corals comprised only 10%
of total C ; in other coral species this value varied between 25 to 40%. In general the parameters of the biomass
of polypso~~d zooxanthellae as well as the metabolic and feeding rates in corals appear to be amazingly constant in
most coral species investigated and are independent of taxonomic position or size of the polyps. Among these
parameters are the biomass of polyps per g of dry weight of coral colony (4-8 mg C g-I), the ratios of biomass of
zooxanthellae to the biomass of polyps (0. 6-1. 3), the coefficients PIB in zooxanthellae (2-5), the rates of photosyn.
thesis (P) and respiration (M) per g of dry weight of colony (100-250 mg C gl dayl), and ratios of PIB (1.2-1.4 per
day). Only in the corals Tubipora, Montipora and Porites was this ratio less than 1. Employing the C14 -method
it was shown that the corals investigated can cover 20 to 70% of their metabolic loss by feeding on the dissolved
organic matter or bacterioplankton at their concentrations close to those in waters over the reef. By utilizing the
preys' concentrations (0. 5-1 mg 1-1 of the biomass) most corals can cover 30 to 100% of their metabolic loss. The
most active predators were found to be the corals with small polyps (Acropora, PocilloporaJ. The opinion that the
corals with small polyps are more autotrophic as compared to corals which have large polyps seems to be
incorrect.

Skeletons of ~ent reef-building corals are mainly composed of aragonite. Coral aragonite gradually
transforms into more stable crystals such as calcite or protodolomite. In order to elucidate the mechanism of this
transformation. the authors have examined factors controlling the transformation through a dissolution experiment.
The experimental results indicate that magnesium ions in solution hinder the transformation from
aragonite to calcite. and then hinder the dissolution of minor elements from original coral aragonite. The present
paper shows the experimental results on the dissolution of minor elements from coral aragonite during the
transformation of the aragonite to calcite.

A study of mucus and mucous aggregates emitted from hard and soft corals of the coral reef complex in front
of Noumea (New Caledonia) was carried out to obtain information about the first stages of their transformation.
Mucus samples at the end of the low spring tide was lyophilized and biochemical compounds were determined.
An important mineral discharge, corresponding in part to salts coming from seawater, was included in the
samples. The protein fraction confirms the relative abundance of dicarboxylic amino acids but a non-protein fraction
(60 to 70% of total nitrogen) is present in polyp mucus. More than a third of dry tissue was represented by
lipids: phospholipids constitute a large fraction of lipids in floating mucous aggregates but sterols are not abundant
in the mucus present at the polyp surface. One of the principal results obtained in this study is the importance
of monoacylglycerides in mucus-lipids.
The establishment of an agreement about sampling techniques is necessary to facilitate comparisons among
different laboratory results.

Growth potential and biological productivity of reef communities can be considered to be directly dependent
upon. genetically determined levels of mineral metabolism in coral polyps and metabolism of their symbionts. To a
considerably smaller extent these Indices depend upon hydrodynamIc conditIons, light and some other environmental
factors. We came to such conclusions on the basis of the comparative analysis of mass-size ratios in
two isolated populations of Porites lobata: from Phantom Bank (northern Australial and the lagoon of the Great
Barrier Reef of New Caledonia, near Noumea.

The Marianas Islands, which form the southern third of an island arc extending from Honshu in the north to
Guam in the south, provide an interesting opportunity for tracing latitudinal changes in species composition of
intertidal animals. Recent collections made by one of us in the northern islands reveal striking differences in
molluscan species composition between these volcanic islands and the southern islands. whose shores are composed
mainly of limestone. The northern islands have a large faunal element of middle to high intertidal gastropods
that is absent from the southern islands. This element consists of typical warm-temperate to subtropical Japanese
species (4 Haliotis species. 9 patellacean species) and of tropical Indo-west Pacific forms confined to continental
coasts and adjacent high islands (Haliotis varia, Nerita chamaeleon, Planaxis niger, two Nodolittorina spei
cies). The fauna of the southern islands contains at least five high intertidal species not found in the northern islands. Two of these (Nerita guamensis and Echininus cumingii spinulosus) are identical with, or closely related
to, species in the Ryukyus; two (Patelloida lentiginosa and Nerita insculpta) are continental species reaching no
farther east than the Marianas; and the fifth species (Planaxis sulcatus) is a wi~spread Indo-west Pacific form
common on the shores of continents as well as oceanic islands.
These differences may have arisen for three reasons: (1) the northern islands are distinctly cooler and, therefore,
may be suitable for warm-temperate Japanese species; (2) the northern islands may be more consistently
under the influence of the Kuroshio Current, since a southern branch, the Subtropical Countercurrent. intermittently
flows eastward from the Taiwan area; Asian affinities of several southern Mariana species suggest that
the Kuroshio influence may once have reached farther south than it does today; (3) the volcanic shores of the
northern islands may be more favorable to high intertidal patellid limpets than are the limestone shores of the
southern islands, as they appear to be in the Philippines and in Indonesia. Latitude. history. dispersal, and
substratum may all playa role in determining gastropod species composition along the Marianas Island arc.

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Bioluminescence in shallow tropical marine fishes is mainly restricted to nocturnally active species which
forage on small motile invertebrates, especially crustaceans. In these fishes, luminous organs are primarily either:
1) ocular light organs or, more commonly, 2) gut-associated light organs. Very few shallow-water species produce
light from dermal photophores. Ocular light organs are of the bacterial type and primarily function in attracting
and detecting prey: Luminescence from gut.associated light organs is produced either from bacteria or from
glands which contain Cypridina.like luciferin. The light from these gut-associated organs is usually expressed externally
as a diffuse ventral glow. This glow, when it matches the characteristics of the downwelling ambient
light, effectively camouflages the fish from any predators or prey which might be below.
The more precise visual acuity of organisms in shallow water may account for the predominance of diffuse
counterillumination among shallow water fishes compared to those of midwaters. In contrast to the diffuse lumi.
nescence of shallow-water fishes, most luminous midwater fishes have discrete ventral photophores. To the less
visually acute organisms of the mesopelagic, this distribution of photophores may produce a counter illuminating
effect similar to that seen in shalllow.water fishes.
The luminescent systems of all shallow-water luminous fishes may have evolved as a consequence of the dietary
connection to crustacean prey; endogenous systems may have arisen from a utilization of the luciferin synthesized
by their crustacean prey (the Cypridina-like system) while bacterial systems may have arisen in conjunction
with chitinase-producing luminous bacteria which aided in the digestion of crustacean exoskeletons.

.Pair.ed sets of caged ~nd exposed Gracilaria edulis thalli were placed at various sites within a coral-reef
habitat m order to determine the amount of browsing by herbivorous reef fishes. Both growth rates of the thalli
and the a~ount o~ brow~mg were dependent upon depth and location within the reef habitat. Growth rates of intact
thalli were highest In. shallow are~s an~ h~rbivore browsing was greatest in the middle depths of the reef
slope. Surveys of the herbivorous reef fishes mdicated that the acanthurid Naso lituratus was probably responsible
for most of the browsing on Gracilaria in this area.

Change in the mechanical properties of the dermis of a sea cucumber (Stichopus chloronotus) was quantitatively
described using tensile tests. The modulus of the dermis was 2 X 104 N.m-2 in artificial seawater. It in.
creased to 13 X 10" N'm-2 in artificial seawater containing 100 mM potassium and to 6 X 10" N.m.2 in the coelomic
fluid of the sea cucumber.
Methanol extraction of the coelomic fluid revealed two factors active on the sea cucumber dermis: the methanol
soluble fraction of the coelomic fluid stiffened the dermis; and the methanol insoluble fraction softened it.
Similarly, the methanol soluble fraction stiffened. and the insoluble fraction softened. the catch apparatus of the
sea urchin spine.
Both the hoiothurian dermis and the catch apparatus of the sea urchin are collagenous connective tissues.
Echinoderms are unique in that they have connective tissues which change their mechanical properties rapidly
and reversibly. The stiffening agents in sea cucumber coelomic fluid may be common factors controlling the
mechanical properties of connective tissues in various echinoderms.

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19.

ICRS4Fortes, M.D.,
1982

Community structure and productivity of microphytic algae in Philippine reefs,

Ninety-four species of microphytic algae were identified from 19 stations. Mangrove coves yielded about 30%
of the total number of species recorded from coral reefs and from those associated with mangroves. Reefs have
consistently higher species diversity indices (HI than coves with mangroves. These findings support the idea that
the degree of algal community similarity and floristic composition may be used as measures of the similarity in
the magnitude of the principal environmental factors, thereby defining a biotic structural distinction between the
habitats.
Productivity of the algae epiphytic on the leaves of the seagrass, Enhalus acoroides, was correlated with the
age and organic matter content of the leaf substrates. The comparatively high values obtained further underlie
the significant role of the epiphytic community in the energy budget of a near-shore ecosystem.

The community structure of coral reef builders (scleractinians and hydrocorals) present in the barrier reefs of
the Caribbean coastline of Mexico (northeast section of Yucatan peninsula) is analyzed. Several reef sampling sections
distributed in more than 40 km of barrier reefs. together with a previous qualitative study of the whole
north section of the same area. allow the authors to consider this study as representative of the coral reef formation
all along the Mexican Caribbean coastline.
These reefs present a poorly developed reef structure. mostly at the fore-reef zone. The coral community in
this zone is physically controlled by harsh environmental conditions as a result of the combined effects of a low
bottom slope. sand accumulation and resuspension of the sediment by wave action. Because of these. the important
reef-building species are practically absent. and population densities are minimal. The dominant species are
those most resistant to existing environmental conditions.
The coral community of the rear zone, and to some extent the one of the breaker zone. is protected from wave action by the low slope of the fore-reef. High population densities, dominance by the typical reef-building species
of the Caribbean and species richness characterize this zoogeographic region.
It is concluded that the atypical configuration observed in these reefs is due to the differences in environmental
severity between the reef zones, a condition that has probably existed for a long period of time.

Replicate collections of Pocillopora verrucosa colonies were taken from lagoon and reef front sites at Moorea
(high island) and Takapoto (atoll) in French Polynesia. All obligate associates collected were found to belong to
the same species pool. but non-obligate associates from Moorea and Takapoto were from different species groups.
Obligate associates occurred in greater numbers than expected at the atoll whereas non-obligates were greater
than expected at the high island lagoon sites. These proportions of obligates and non-obligates fit well with
Abele's environmental variability hypothesis. An additional hypothesis that high benthic productivity enables
colonies to support greater numbers of non-obligates also may explain the proportions of associates found in this
study.

Most of the quantitative studies of coral reef hard bottom communities are conducted with quadrat or
transect line methods. To provide a basis of comparison of these two techniques, quadrat and transect line
sampling methods have been used for the quantitative study of fringing reef scleractinian coral communities of
Reunion Island (Indian Ocean). Statistical analysis showed that there was no significant difference between the
results obtained by using both techniques. However. the line transect method appeared to be quicker and simpler
to use in the field.

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23.

ICRS4Hodgson, V.S.,
1982

Conditioning as a factor in the symbiotic feeding relationship of sea anemones and anemone fishes,

Several species of anemonefishes were obSf!r:ved in the field storing food among: the tentac}es and i.n the
pharynx of reef anemones when under competitive pressure from the more aggressive damselfishes. Prior to
deposition of food. anemones were observed to open their mouth as the fish approached through the tentacles. This
behavior was not seen when anemonefish rested or swam among the tentacles. When the symbionts were removed
from the reef to the laboratory. the food storage behavior of the fish was decreased over time in the absence of
competition from other fishes.
Anemones without fish symbionts had previously been subjected to conditioning trials which elicited mouth
opening in response to a mild mechanical stimulus prior to receiving food. This behavior resembled the mouth
opening associated with the food storage activity of the anemonefish. The ease of modifying the behavior of anemones
in response to tactile stimuli suggests that the mouth opening behavior of reef anemones could be a type of
conditioned response to the food carrying motions of the anemonefish. Such interspecific associative behavior
could playa larger role in the ecological adaptations of reef symbionts than hitherto suspected.

The coral and fish taxocenes of coral communities around a nearshore. high island were sampled quantitatively
along 4 transects and compared in terms of abundance. richness. diversity. and evenness trends. Correlations
between fish and coral indices were generally low or non'significant. Dendrographs were prepared of quadrats
based on their associated fish species, coral growth forms. coral genera. and coral genera/form combinations.
Geographic correspondence between the fish and coral clusters is poor. The analyses provide complementary des.
criptions of the coral communities from different aspects.

A fringing reef consisting of a broad reef flat. reef crest. and reef wall was sampled using parallel transect
lines perpendicular to the depth gradient. Separate analyses were conducted based on the coral cover and the
colony counts of the 204 species encountered. Dendrographs based on the two approaches yielded slightly dift
feren.t zone classifications.attri~uta.ble to a bias towards large spreadin?, colonies in the former case and an emphasIs
on small. abundant colonies In the latter.
The study reef is characterized by low diversity stands of Pavona decussata and Cycloseris patelliformis on
the reef flat. dense stands of ramose and foliose Montipora colonies on the upper reef crest. a lower reef crest with
Porites nigrescens. and a high diversity of species and colony forms on the reef wall dominated by Pavona
praetorta.